1. Field of the Invention
The present invention relates to self-foaming creams in the form of a pressurizable oil-in-water emulsion, as well as to post-foaming pressurized devices containing them. These creams for topical use have good foaming power and are intended more particularly to cleanse and care for the skin.
2. Description of the Background
Cleansing the skin is very important for facial care. It must be as efficient as possible, since greasy residues such as excess sebum, the residues of the cosmetic products used daily and make-up products, in particular waterproof products, accumulate in the folds and at the surface of the skin and may obstruct the pores, leading to the development of spots. Among other causal factors, poor quality cleansing is often responsible for a muddy complexion.
Several major types of skin cleansing products are known such as foaming detergent aqueous gels and lotions and rinsable cleansing anhydrous gels and oils, cleansing milks and foaming creams, which are usually soap-based.
Foaming detergent aqueous gels and lotions have a cleansing action imparted by surfactants which place the fatty residues and the pigments of the makeup products in suspension. They are cosmetically pleasant and efficient because they foam and they are easily removed. Since they contain no cosmetic oil, they have the drawback of drying the skin by their delipidating action. This is the case, for example, of the products described in WO 95/05769, which teaches very fluid, pressurizable skin cleansing lotions which produce a beautiful mousse, but these products destroy the skin's hydrolipid film and leave the skin clean but rough.
Rinsable anhydrous gels and oils have a cleansing action by means of the oils contained in these formulations. These oils make it possible to dissolve greasy residues and to disperse make-up pigments. These products are efficient and well-tolerated. They have the drawback of being heavy, of not foaming and of not giving a sensation of freshness when applied, which is detrimental in cosmetic terms.
Cleansing milks and creams contain both detergent surfactants, emulsifiers and oils in sufficiently low amounts so as not to destabilize the emulsion. Despite their good efficacy, these products are non-foaming and are of insufficient rinsability, thus making it necessary to use an additional detergent tonic lotion in order to improve the rinsing and the removal of soiling. Besides its astringent nature, the use of this second product may lead to long-term drying of the skin.
An existing objective has been to design cleansing foaming products that are fully rinsable with water, containing few or no surfactants and able to comprise oils in large amounts if so desired, in order to optimize the cleansing of the skin and to moisturize and nourish it by avoiding any drying or irritation of the skin. A desired objective is a cream which has the efficacy of a soap cream (cleansing power and foaming), but not its drawbacks, in particular the stripping of the skin which is associated with a large percentage of foaming surfactants.
In order to produce such a product, it is not possible simply to introduce oils into an aqueous gel or lotion, since oils tend to inhibit the foaming properties of these formulations, that is, the oils are said to "kill" the foam. Furthermore, the dispersion of the oil is unstable. Foaming emulsions, for example cleansing emulsions, are known as shown in WO 95/17163. This type of product is very mild and very well-tolerated by the skin, but the foaming power of these emulsions is low because of the presence of oils. In addition, these emulsions are relatively thick, which does not allow them to be packaged in pressurized containers.
Moreover, it is known, for example, as taught in WO 89/11907, that the phase inversion method makes it possible to prepare stable, fluid oil-in-water emulsions. However, the emulsions prepared by the phase inversion method in the prior art are non-foaming and are delivered in the form of spray when they are pressurized. In addition, they comprise appreciable amounts of surfactants.
Creams in the form of foaming, pressurized oil-in-water emulsions, comprising at least 2% of a nonionic surfactant, up to 21% of oil and from 0.5-4.5% of a consistency agent, are known as described in U.S. Pat. No. 4,808,388. Such compositions are only delivered in a satisfactory manner (sheen, firmness. density) if CO.sub.2 or N.sub.2 O is used as the propellant gas. A need continues to exist for an improved self foaming skin or hair treating composition.